Stroboscopic Time-of-Flight Neutron Diffraction in Long Pulsed Magnetic Fields

We present proof-of-principle experiments of stroboscopic time-of-flight (TOF) neutron diffraction in long pulsed magnetic fields. By utilizing electric double-layer capacitors, we developed a long pulsed magnet for neutron diffraction measurements, which generates pulsed magnetic fields with the full widths at the half maximum of more than $10^2$ ms. The field variation is slow enough to be approximated as a steady field within the time scale of a polychromatic neutron pulse passing through a sample placed in a distance of the order of $10^1$ m from the neutron source. This enables us to efficiently explore the reciprocal space using a wide range of neutron wavelength in high magnetic fields. We applied this technique to investigate field-induced magnetic phases in the triangular lattice antiferromagnets CuFe$_{1-x}$Ga$_x$O$_2$ ($x=0, 0.035$).Comment: 9 pages, 7 figure

マルチフェロイックCuFeO2における交差相関現象に関する研究

東京理科大学201

Recent Progress on DNA ToF Backscattering Spectrometer in MLF, J-PARC

DNA is a time-of-flight backscattering neutron spectrometer installed at the Materials and Life Science Experimental Facility in J-PARC. After opening user program, we have been developing and upgrading DNA. The energy resolution is improved and achieved the designed value of 1.4 μeV by renewing the disks of the pulse shaping chopper that can rotate at max 300 Hz instead of 225 Hz of the previous disks. The installation of Si311 analyser mirrors has been almost accomplished, which extends momentum transfer region up to 3.7 Å-1. We demonstrate the effect of this extension by measuring and analysing methyl rotation dynamics in solid toluene at 10 K and 40 K. We also report variety of sample environment available at DNA and their remote handling

Atomic reconstruction induced by uniaxial stress in MnP

Abstract In condensed matter physics, pressure is frequently used to modify the stability of both electronic states and atomic arrangements. Under isotropic pressure, the intermetallic compound MnP has recently attracted attention for the interplay between pressure-induced superconductivity and complicated magnetic order in the vicinity . By contrast, we use uniaxial stress, a directional type of pressure, to investigate the effect on the magnetism and crystal structure of this compound. An irreversible magnetisation response induced by uniaxial stress is discovered in MnP at uniaxial stress as low as $$0.04\ \text {GPa}$$ 0.04 GPa . Neutron diffraction experiments reveal that uniaxial stress forms crystal domains that satisfy pseudo-rotational symmetry unique to the MnP-type structure. The structure of the coexisting domains accounts for the stress-induced magnetism. We term this first discovered phenomenon atomic reconstruction (AR) induced by uniaxial stress. Furthermore, our calculation results provide guidelines on the search for AR candidates. AR allows crystal domain engineering to control anisotropic properties of materials, including dielectricity, elasticity, electrical conduction, magnetism and superconductivity. A wide-ranging exploration of potential AR candidates would ensure that crystal domain engineering yields unconventional methods to design functional multi-domain materials for a wide variety of purposes